ITPA Topical Group on MHD, Control, and Disruptions Summary of 5th meeting, Nov. 8-10, 2004 Presented by Ted Strait Workshop on MHD Mode Control Princeton, Nov. 23, 2004 More information at

ITPA Topical Group on MHD, Control, and Disruptions Fifth meeting: Lisbon, Nov New chairman: Tim Hender Scope now includes energetic ion modes –Formerly in Steady State group U.S. attendees: Ted Strait, Michio Okabayashi, Jon Menard, Eric Hollmann, Ed Lazarus U.S. members: Ted Strait, Steve Jardin, Bob Granetz, Jerry Navratil, John Wesley, Ed Lazarus

Physics topics Joint sessions with other ITPA groups –Stability limits and transport with strong RS and transport barriers: (with Transport Physics group) –“Physics versus drsep” (with Pedestal, Divertor, Transport, Confinement, and Steady-State groups) Additional technical talks –Beta-limiting instabilities and their control (NTM, RWM) –Disruption physics, prediction, avoidance and mitigation –Magnetic control of plasma equilibrium (including error fields)

Tokamak Physics Basis for Burning Plasma –Update of ITER Physics Basis ( Nucl. Fusion 39 No. 12, Dec. 1999) Chapter 3. MHD Stability, Operational Limits and Disruptions Chapter 8. Plasma Operation and Control –Now editing sub-sections for balance and length Editors for Chapters 3&8: V. Pustovitov and J. Wesley –Deadline for final draft: Dec. 31 To be submitted to journal by March 31 Tokamak Physics Basis Document

New projects Initiation of new Disruption Database –To include conditions preceding disruption, disruption dynamics, disruption effects, scalar and vector data –Coordinator: J. Wesley –Goal: first draft of variables for the database by Dec. 31 Proposal to develop a common form for the modified Rutherford equation (for benchmarking models and experiments) –Initial goal is to agree on the general form and definitions of parameters, not the specific numerical values –Coordinated by Y. Gribov and H. Zohm

Discussion of joint experiments MDC1 Pressure and size scaling of gas jet penetration for disruption mitigation. –No direct comparisons yet –Expts ongoing or planned in C-Mod, DIII-D, JET, JT-60U, Tore Supra MDC2 Joint experiments on resistive wall mode physics. –Resonant field amplification experiment started (DIII-D, JET) –RFA and critical rotation frequency experiments planned (DIII-D, JET, JT-60U, NSTX, Textor) MDC3 Joint experiments on neoclassical tearing modes (including error field effects) –3/2 beta rampdown experiments done (AUG, DIII-D, JET, JT-60U) –2/1 beta rampdown and error field experiments planned (AUG, DIII-D, JET, others?) MDC4 Neoclassical tearing mode physics - aspect ratio. –No direct comparisons yet –AUG / MAST experiment planned (DIII-D / NSTX in 2006?)

Discussion of joint experiments MDC5 Comparison of sawtooth control methods for neoclassical tearing mode suppression. –Some experiments in 2003 but none in –Experiments planned in AUG, DIII-D, HL2A, JET, NSTX, TCV MDC6 Error field sideband effects for ITER (low beta) –Non-dimensional scaling done (C-Mod, DIII-D, JET) –Need to resolve DIII-D comparison, and Bt scaling in C-Mod –Possible future expts in C-Mod, DIII-D, JET, MAST, NSTX, Textor MDC7 Improving NTM modelling/ extrapolation to ITER –Modified Rutherford equation benchmarked without ECCD stabilization (AUG, DIII-D, JET) and with ECCD (AUG, DIII-D) –Possible joint experiments on pre-emptive ECCD (DIII-D, JT-60U, possibly AUG) –Possible expts on current drive width (AUG, DIII-D, possibly JT-60U) MDC8 Joint experiment on fast ion physics (new topic) –Under discussion by fast ion experts

Plans for next meeting Next meeting (tentatively): Tarragona, Spain –Immediately before or after EPS meeting June 28-July 2 Focus topics for next meeting –Disruption database - working group meeting –NTM physics: (  * scaling, seeding) Common form for modified Rutherford eqn. Benchmark numerical values vs. experiment –Benchmarking of RWM feedback codes (without rotation) Feedback requirements for ITER Effect of noise, noise amplitude in present experiments